Conventionally, a vehicle is generally designed to allow not only a driver who is an occupant but also other occupants to ride in the vehicle. However, in many cases, only the driver rides in the vehicle, which results in wasteful consumption of energy. In views of this, a vehicle, such a tricycle or a four-wheel vehicle, which has a single seat has been provided.
However, in such a single seat vehicle, the position of the centroid becomes higher when a driver rides in the vehicle. Therefore, stability at the time when the driver turns the vehicle; i.e., stability during turning (hereinafter referred as “turning stability”), decreases. In order to overcome this drawback, there has been proposed a single seat vehicle which is inclined toward the turning center at the time of turning to thereby increase the turning stability (see, for example, Patent Document 1).    Patent Document 1: Japanese Patent Application Laid-Open (kokai) No. 2005-88742